Fork-shaped contact spring to produce a separable electric connection

ABSTRACT

An electrical contact element of the two-fingered spring-like contact type is formed so that the spaced contact fingers are folded along an axis parallel to the fingers and extend normal to the plane of the attaching flange and are also bent about an axis extending between them so that each contact finger forms the arm of a V. A retaining flange is wrapped around the folded contact element to retain the contact fingers in their overlapped relationship.

United States Patent [191 Grenda [451 Apr. 10, 1973 1 FORK-SHAPED CONTACT SPRING TO PRODUCE A SEPARABLE ELECTRIC CONNECTION [75] Inventor: Hans August Herbert Grenda, D-

7758 Meersburg, Germany [73] Assignee: Holzer Patent AG, Zug, Switzerland [22] Filed: Mar. 19, 1971 [21] Appl. NOJ 125,961

[30] Foreign Application Priority Data Mar. 20, 1970 Switzerland ..4229/70 [52] US. Cl. ....339/258 R, 339/176 MP, 339/276 SF [51] Int. Cl. ..H01r 11/22 [58] Field of Search ..339/176, 217, 258, 339/259, 276 SF [5 6] References Cited UNITED STATES PATENTS 3,104,925 9/1963 Macnamara ..339/217 S 3,262,088 7/1966 West ..339/258 R 3,414,871 12/1968 Tuchel ..339/2l7 S FOREIGN PATENTS OR APPLICATIONS 1,085,584 7/1960 Germany ..339/258 R 1,109,373 4/1968 Great Britain ..339/276 SF 1,170,256 11/1969 Great Britain ..339/176 MP OTHER PUBLICATIONS National Connector Corp., Form No. 1003, 1963-01.

Primziry Examiner.1oseph H. McGlynn AttorneyWatson, Cole, Grindle & Watson,

[ ABSTRACT An electrical contact element of the two-fingered spring-like contact type is formed so that the spaced contact fingers are folded along an axis parallel to the fingers and extend normal to the plane of the attaching flange and are also bent about an axis extending between them so that each contact finger forms the arm of a V. A retaining flange is wrapped around the folded contact element to retain the contact fingers in their overlapped relationship.

2 Claim, 2 Drawing Figures FORK-SHAPED CONTACT SPRING TO PRODUCE A SEPARABLE ELECTRIC CONNECTION The invention relates to a fork-shaped contact spring to produce separable electric connections, especially for printed circuit boards and, for pressing onto electric conductors, for example, electric cables, with contact fingers made of double the material thickness, by folding an essentially symmetrical element punched from flat, strip-like material.

Contact springs of the initially mentioned type have been known. Thus, for example, in the German Utility Patent No. l.998,542, a contact spring is described in which, among other things, the seam of the contact fingers coincides with the contact travel. At every point of contact, two adjoining contact fingers are pressed via corresponding projections. The disadvantage of this contact terminal is that great precision is required for the bending of the contact fingers toward each other, so that the contact making projections are aligned precisely. Another drawback of the contact terminal results from the fact that, after bending the contact fingers, the already bent contact fingers will again bend upwards because of the twisting of the ribbon-shaped material during the further processing steps. The twisted contact fingers then are caught by the finishing installations so that the danger of a complete breaking off of the contact terminal from the ribbon material occurs. The contact terminal, furthermore, has the disadvantage that in the later operation the contact fingers can again spread apart, since they have noretaining device whatever.

It is the object of the invention, while avoiding the drawbacks of the contact spring, to create such a spring in which the contact fingers, after punching and bending, during the succeeding processing steps will remain in that plane which is determined by the bending. Another object of the invention is to develop the contact spring in such a way thata high contact pressure and several contact supports develop. The finishing process is to be made as simple as possible so that a precise alignment is not necessary for folding up the contact elements. The contact spring, according to a further object of the invention and especially in the case of its contact making supports, is to be shaped in such a way that the contact spring will have a stable seat on a printed circuit board so that it cannot twist. According to the invention, the previously mentioned objectives are achieved through the fact that the two essentially symmetrical contact elements, which are independent per se, are connected along their folding line, are punched from moving sheet material and still carried by said sheet material, and can be folded up mutually and can be fixed in this position by way of a flange for other finishing processes.

According to one development of the invention, the

tachment of the cable lies parallel to the plug-in direction.

Another development of the invention provides that the longitudinal axis of the attaching flange for the attachment of the cable is angled to the plug-in direction.

According to an efiective development of the invention, each time the adjoining contact fingers are bent around their longitudinal axis in such a way that the inside edges opposite the printed circuit board will touch and the edges resting on the printed circuit board are removed from one another.

As compared to known contacts, the object of the application is advantageous in that the fork spring can be produced by relatively simple means. As soon as the two individual contact elements are folded together and are secured by a flange, the entire contact spring lies essentially in one plane. During the following processing steps therefore, no elements already standing up or abutting against the processing arrangements will be damaged as a result of twisting the ribbon shaped starting materials. An unintended breaking of not yet finished contact springs will effectively be avoided thereby. Furthermore, the inventive contact spring, as compared to known springs, has the advantage that, in the case of folding, the requirements for precision do not have to be too high, since after the folding has been accomplished, the contact spring can repunched, as a result of which an absolutely certain matching of the contact fingers lying one on top of the other will be achieved. By twisting the contact fingers in relation to one another, one will additionally achieve the advantage that the contact spring will be able to be seated completely straight on a printed circuit board.

The invention is explained on the basis of an embodiment given by way of example and with the aid of drawings. In the drawings:

FIG. I shows, in perspective presentation, the individual processing steps leading to the finished contact spring,

I FIG. 2 shows a top view of contact fingers bent around their longitudinal axis and which rests on a flange serves initially for the fixation of the contact spring in a contact housing.

According to another development of the invention, the folded contact elements are repunchable in order to achieve an exact measurement.

According to a further development of the invention, the contact elements are oversize and can be repunched after being folded.

According to another development of the invention, the longitudinal axis of the attaching flanges for atprinted circuit board.

From FIG. 1 it is clear that, first of all, the forkshaped contact spring is punched out of a band-shaped flat material 1. The punched part resulting therefrom has two contact elements 2, each of which has two contact fingers 6. The first of the two contact elements 2 is provided, moreover, with an attaching flange 5 which, after appropriate shaping, is to serve later on to hold a cable. Contact element 2 connected with the attaching flanges 5 has been connected in addition with the bandshaped starting material via its contact fingers at their ends. The attaching flanges 5 likewise are still in connection with the bandshaped starting material. The second contact element 2 is' connected merely by means of a folding line 3 with the first contact element.

As soon as processing step A has been carried out, process step B follows, which consists in the freely punched contact element 2 being bent onto the other contact element 2 attached to the band-shaped starting material 1. In the next processing step C, flange 4 then is bent in such a way that it will firmly hold the two contact elements 2 together. At the same time, flange 4 constitutes in a known manner the stop of the contact spring in a contact housing.

As soon as processing step C has been executed, it is therefore possible with the contact spring formed in such a way and attached to the band material to carry out the succeeding processing steps without danger; that is to say--contrary to the known contact springsit is not possible in-the case of the object of the application for the individual parts of the contact spring on the basis of tilting, twisting or bending of the band-shaped material to assume an erect position and thus abut against various places of the finishing arrangements and cause the entire spring to break off. Other finishing steps can thus be accomplished safely. A further finishing step, the deforming of the attaching flange 5, for example, is to be considered, which-as already mentionedis supposed to serve for the holding of the ca ble. As a further finishing step, the subsequent punching of the individual contact elements 2, which already lie one above the other, is to be considered. This subsequent punching leads to the outside limiting edges of the two contact elements 2 being precisely identical. Insofar as the subsequent punching is a constituent part of the finishing process of the'fork-shaped contact spring, the two contact elements 2 are given a certain oversize in the case of the first punching step and given the final dimensions only through the subsequent punching.

As can be seen in FIG. 2, the individual contact fingers 6 can be bent approximately as a V toward each other in such a way that edges 9, resting on the conducting path 8 of a printed circuit board 7, are

separated from one another, while the opposite edges 9, which therefore do not rest on the conducting paths 8, will touch or at least face each other at very close range. This form of the contact finger 6 is advantageous because the finished fork-shaped contact spring will always just rest on the printed circuit board. A twisting of the contact spring in the case of this type of embodiment is not possible.

What is claimed is:

1. An electrical contact element of the type having two-fingered spring-like contact elements and being formed from sheet-like material, comprising:

an attaching flange for connecting said contact element to an electrical cable;

a contact element connected to said attaching flange and including a pair of spaced contact fingers formed by folding said contact element along an axis parallel to said contact fingers, said pair of contact fingers extend normal to the plane of said attaching flange, said contact fingers are bent about an axis extending between them so that each contact finger forms the arm of a V; and

a retaining flange wrapped around said folded contact element for retaining said contact-fingers in said overlapped relationship.

2. An electrical contact element as in claim 1 wherein the free end portions of said contact fingers have respective flat surfaces and said flat surfaces are facing one another. 

1. An electrical contact element of the type having two-fingered spring-like contact elements and being formed from sheet-like material, comprising: an attaching flange for connecting said contact element to an electrical cable; a contact element connected to said attaching flange and including a pair of spaced contact fingers formed by folding said contact element along an axis parallel to said contact fingers, said pair of contact fingers extend normal to the plane of said attaching flange, said contact fingers are bent about an axis extending between them so that each contact finger forms the arm of a V; and a retaining flange wrapped around said folded contact element for retaining said contact fingers in said overlapped relationship.
 2. An electrical contact element as in claim 1 wherein the free end portions of said contact fingers have respective flat surfaces and said flat surfaces are facing one another. 